Connect to different validators on different leaves (#1966)

* Connect to different validators on different leaves

* Implement ConnectionRequests

* Replace existing connection request

* Do not terminate if there are no ongoing requests

* Adds tests

* Remove the loop

* Add replacement test

* Use find

* Update node/subsystem-util/src/validator_discovery.rs

Co-authored-by: Andronik Ordian <[email protected]>

* Add requests revocation to cleanup

* Revert "Add requests revocation to cleanup"

This reverts commit d0ac1d7a0672f0ba803c923a32ca6ca84538f549.

Co-authored-by: Andronik Ordian <[email protected]>